Cold hardiness & minimum temperature

Is Mimulus ringens (Mimulus ringens)cold hardy? Hardiness zone & min temp

Also called Allegheny Monkeyflower, Square-Stemmed Monkeyflower.

More about mimulus ringens

About Mimulus ringens

Mimulus ringens · also called Allegheny Monkeyflower, Square-Stemmed Monkeyflower · flowering

Allegheny monkeyflower is an upright North American wetland perennial of marshes, wet meadows and stream banks. Square stems carry paired, lance-shaped leaves and a long summer succession of two-lipped, lavender-blue flowers loved by bumblebees and hummingbirds. A reliable, well-behaved marginal for bog gardens and rain gardens, it needs steady moisture and an open, sunny position to perform.

Cold limit: USDA 3-9 · RHS H6 (5-28°C)

What mimulus ringens's hardiness rating actually means

Yes — mimulus ringens is genuinely cold hardy. Rated RHS H6 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 3-9 — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about −20 to −15 °C. Mimulus ringens is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for mimulus ringens as it gets too cold:

It tolerates winter lows to about −20 to −15 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can mimulus ringens go outside or overwinter — and where?

Plant it out within USDA 3-9 and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when mimulus ringens can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Mimulus ringens hardiness — frequently asked questions

Is mimulus ringens cold hardy?

Yes — mimulus ringens is genuinely cold hardy. Rated RHS H6 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Mimulus ringens is hardy across USDA 3-9; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature mimulus ringens can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Mimulus ringens is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is mimulus ringens?

Mimulus ringens is rated USDA 3-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can mimulus ringens survive winter outside?

Plant it out within USDA 3-9 and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to mimulus ringens below its minimum temperature?

It tolerates winter lows to about −20 to −15 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.